Writing servo wedge code to a disk is disclosed. A wedge-to-wedge time interval is determined. At least until it is determined that a lock criterion is met: For each wedge-to-wedge time interval, a wedge frequency error is computed based on an adjustable clock. The clock is adjusted based on one or more of the wedge frequency errors. It is determined whether a lock criterion is met based on one or more of the wedge frequency errors. After the lock criterion is met, servo wedge code is written to the disk.
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1. A method for writing servo wedge code to a disk, comprising: determining a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met, using a processor to: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; after the lock criterion is met, writing servo wedge code to the disk; and in the event one of the plurality of wedge frequency errors exceeds a maximum wedge frequency error, setting that wedge frequency error to 0.
A method for writing servo wedge code to a disk involves first determining the time interval between wedges. Until a "lock" is achieved, a processor calculates a frequency error for each wedge interval using an adjustable clock. The clock is adjusted based on these frequency errors, and a check is performed to see if the "lock" condition is met based on the frequency errors. Once locked, the servo wedge code is written to the disk. If any frequency error exceeds a limit, it's reset to zero.
2. A method as recited in claim 1 , wherein for each wedge-to-wedge time interval, the clock is adjusted based at least in part on the wedge frequency error associated with that wedge-to-wedge time interval.
Building on the method of writing servo wedge code described previously, the adjustable clock is adjusted for each wedge-to-wedge time interval, based at least in part on the frequency error associated with *that* specific time interval. This ensures the clock is reacting to the most recent frequency error measurement.
3. A method as recited in claim 1 , wherein the wedge-to-wedge time interval is determined based at least in part on the total number of servo wedges to be written.
In the method of writing servo wedge code, the determined time interval between wedges is based, at least partially, on the total number of servo wedges that need to be written to the disk. The more wedges needed, the shorter the time interval between them.
4. A method as recited in claim 1 , wherein computing a wedge frequency error includes: detecting a known mark in a spiral segment in an intersection of a spiral waveform with a track on a disk; determining a current detection time indication associated with a time when the known mark was detected; and computing the wedge frequency error based at least in part on the current detection time indication and a previous detection time indication.
In the servo wedge writing method, calculating the frequency error includes: finding a specific marker within a spiral section where a spiral waveform meets a track on the disk; recording the exact time this marker was found; and calculating the frequency error using this time and the time the same marker was found previously.
5. A method as recited in claim 4 , wherein the previous detection time indication is associated with the time of detection of the same known mark in a previous revolution.
Expanding on the frequency error calculation, the "previous detection time" from the servo wedge writing method refers to when the same marker was detected in the *previous* rotation of the disk. This allows tracking changes across full rotations.
6. A method as recited in claim 4 , wherein computing the wedge frequency error includes taking the difference between a current detection time indication and a previous detection time indication.
Refining the frequency error calculation, in the servo wedge writing method, the error is found by simply subtracting the previous detection time from the current detection time. The difference in these times becomes the wedge frequency error.
7. A method as recited in claim 4 , further including determining whether the known mark needs to be changed due to a servo wedge being written over the known mark and in the event that the known mark needs to be changed, changing the known mark.
The servo wedge writing method includes a step to check if a marker needs to be changed because a servo wedge has been written over it. If a marker has been overwritten, the method updates the marker.
8. A method as recited in claim 4 , wherein there are two intersections per wedge-to-wedge time interval.
Further specifying the servo wedge writing method, there are *two* intersections between a spiral waveform and a track on the disk for *each* wedge-to-wedge time interval.
9. A method as recited in claim 1 , wherein the lock criterion is met when, for each wedge-to-wedge time interval, the absolute value of the corresponding wedge frequency error is within a wedge frequency error limit for a predefined number of consecutive disk revolutions.
In the servo wedge writing method, the "lock" condition is considered met when, for each wedge-to-wedge time interval, the *absolute value* of the frequency error is within a defined limit for a certain number of consecutive disk revolutions. This ensures stability before writing.
10. A method as recited in claim 1 , wherein after the lock criterion is met, computing a wedge frequency error is performed differently from before the lock criterion is met.
The servo wedge writing method changes *how* the frequency error is calculated *after* the lock criterion is met, compared to how it was calculated before locking.
11. A method as recited in claim 1 , wherein the lock criterion is met if each of the plurality of wedge frequency errors is less than a wedge frequency error limit for a certain number of disk revolutions.
The servo wedge writing method achieves "lock" if *every* frequency error is below a certain limit for a certain number of rotations of the disk.
12. A method as recited in claim 11 , wherein after the lock criterion is met, the adjustable clock resets at the same circumferential location in each wedge-to-wedge time interval on every disk revolution, within a wedge frequency error limit.
Expanding on achieving "lock", once achieved in the servo wedge writing method, the adjustable clock resets at the same circumferential location in each wedge-to-wedge time interval on *every* disk rotation, remaining within a defined frequency error limit.
13. A method as recited in claim 1 , wherein the clock is adjusted based at least in part on an output of a loop filter that takes the wedge frequency error as input.
In the servo wedge writing method, the adjustable clock is adjusted based, at least in part, on the output of a "loop filter". This filter takes the frequency error as input and smooths or modifies it before adjusting the clock.
14. A method as recited in claim 13 , wherein the loop filter includes an accumulator configured to sum two or more of the plurality of wedge frequency errors.
Further clarifying the loop filter, the servo wedge writing method uses an accumulator *inside* the loop filter. This accumulator adds up two or more frequency errors to help smooth out variations and improve lock stability.
15. A method for writing servo wedge code to a disk, comprising: determining a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met, using a processor to: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; and after the lock criterion is met, writing servo wedge code to the disk, wherein after the lock criterion is met, the wedge frequency error is computed based at least in part on one or more of the following: a target detection time indication defined as the value of the time stamp when changing to the lock state; or a target detection time indication that stays the same during the lock state.
A method for writing servo wedge code to a disk involves determining the time interval between wedges. Until a "lock" is achieved, a processor calculates a frequency error for each wedge interval using an adjustable clock, adjusts the clock, and checks if the "lock" condition is met. Once locked, servo wedge code is written. After the lock is achieved, the frequency error is calculated based on either: the timestamp value when the lock state was entered; or a fixed, unchanging timestamp defined as the target detection time.
16. A method for writing servo wedge code to a disk, comprising: determining a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met, using a processor to: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; and after the lock criterion is met, writing servo wedge code to the disk, wherein: the lock criterion is met if each of the plurality of wedge frequency errors is less than a wedge frequency error limit for a certain number of disk revolutions; and the adjustable clock resets N wedge times per disk revolution, where N wedge is the number of wedges on the disk.
A method for writing servo wedge code to a disk involves determining the time interval between wedges. Until a "lock" is achieved, a processor calculates a frequency error for each wedge interval using an adjustable clock, adjusts the clock, and checks if the "lock" condition is met. Once locked, servo wedge code is written. Lock is achieved if every frequency error is below a limit for a number of disk rotations. The adjustable clock resets N times per disk revolution, where N is the number of wedges on the disk.
17. A system for writing servo wedge code to a disk, comprising: a processor configured to: determine a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; after the lock criterion is met, write servo wedge code to the disk; and in the event one of the plurality of wedge frequency errors exceeds a maximum wedge frequency error, setting that wedge frequency error to 0; and a communication interface coupled to the processor.
A system for writing servo wedge code to a disk includes a processor and a communication interface. The processor determines the wedge-to-wedge time interval. Until a "lock" criterion is met, the processor calculates a frequency error for each wedge interval using an adjustable clock, adjusts the clock based on these errors, and determines if the "lock" condition is met. Once locked, the processor writes the servo wedge code. If any frequency error exceeds a limit, it's reset to zero.
18. The system recited in claim 17 , wherein the processor is configured to compute a wedge frequency error at least in part by: detecting a known mark in a spiral segment in an intersection of a spiral waveform with a track on a disk; determining a current detection time indication associated with a time when the known mark was detected; and computing the wedge frequency error based at least in part on the current detection time indication and a previous detection time indication.
In the servo wedge writing system, the processor calculates the frequency error by: finding a specific marker within a spiral section where a spiral waveform meets a track on the disk; recording the exact time this marker was found; and calculating the frequency error using this time and the time the same marker was found previously.
19. A system as recited in claim 17 , wherein the lock criterion is met when, for each wedge-to-wedge time interval, the magnitude of the corresponding wedge frequency error is within a wedge frequency error limit for a predefined number of consecutive disk revolutions.
In the servo wedge writing system, the "lock" condition is met when, for each wedge-to-wedge time interval, the magnitude of the frequency error is within a defined limit for a certain number of consecutive disk revolutions.
20. A system as recited in claim 17 , wherein after the lock criterion is met, computing a wedge frequency error is performed differently from before the lock criterion is met.
The servo wedge writing system changes *how* the frequency error is calculated *after* the lock criterion is met, compared to how it was calculated before locking.
21. A system as recited in claim 17 , wherein the system is in a search state before the lock criterion is met and the system is in a lock state after the lock criterion is met.
The servo wedge writing system operates in a "search" state before the lock criterion is met, and switches to a "lock" state after the criterion is satisfied.
22. A system for writing servo wedge code to a disk, comprising: a processor configured to: determine a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; and after the lock criterion is met, write servo wedge code to the disk, wherein after the lock criterion is met, the wedge frequency error is computed based at least in part on one or more of the following: a target detection time indication defined as the value of the time stamp when changing to the lock state; or a target detection time indication that stays the same during the lock state; and a communication interface coupled to the processor.
A system for writing servo wedge code to a disk includes a processor and communication interface. The processor determines the wedge-to-wedge time interval. Until a "lock" is achieved, the processor calculates a frequency error for each wedge interval using an adjustable clock, adjusts the clock, and checks if the "lock" condition is met. Once locked, servo wedge code is written. After lock, the frequency error is calculated based on either: the timestamp value when the lock state was entered; or a fixed, unchanging timestamp that remains the same during the lock state.
23. A system for writing servo wedge code to a disk, comprising: a processor configured to: determine a wedge-to-wedge time interval; at least until it is determined that a lock criterion is met: for each wedge-to-wedge time interval, compute a wedge frequency error based on an adjustable clock to obtain a plurality of wedge frequency errors; adjust the clock based on one or more of the plurality of wedge frequency errors; and determine whether a lock criterion is met based on one or more of the plurality of wedge frequency errors; and after the lock criterion is met, write servo wedge code to the disk, wherein: the lock criterion is met if each of the wedge frequency errors is less than a wedge frequency error limit for a certain number of disk revolutions; and the adjustable clock resets N wedge times per disk revolution, where N wedge is the number of wedges on the disk; a communication interface coupled to the processor.
A system for writing servo wedge code includes a processor and communication interface. The processor determines the wedge-to-wedge time interval. Until a "lock" is achieved, the processor calculates frequency error for each wedge interval using an adjustable clock, adjusts the clock, and checks if "lock" is met. Once locked, servo wedge code is written. "Lock" is achieved if every frequency error is below a limit for a number of disk rotations. The adjustable clock resets N times per disk revolution, where N is the number of wedges on the disk.
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April 5, 2011
August 20, 2013
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